irresponsibility vs thoughtlessness

irresponsibility

noun
  • The character or state of being irresponsible; lack of or freedom from responsibility; want of accountability. 

thoughtlessness

noun
  • heedless disregard for the consequences of one's actions 

  • disregard for other's feelings 

How often have the words irresponsibility and thoughtlessness occurred in a corpus of books? (source: Google Ngram Viewer )